Fluorocarbon compounds



United States Patent FLUOROCARBON COMPOUNDS George H. Smith, New Canada Township, Ramsey County, Minm, assignor to Minnesota Mining & Manufacltzring Company, St. Paul, Minn., a corporation of De ware No Drawing. Application July 17, 1953, Serial No. 368,820

4 Claims. (Cl. 260-561) This invention relates to my discovery of a new and useful class of reactive fluorocarbon compounds which are perfluoro secondary amides.

More specifically, the present compounds are aliphatic diperfluoroacylamides represented by the generic formula:

which can be abbreviated as:

(RrCO) (R1CO)NH where R1 and R: are perfluoroalkyl groups (which may be the same or difierent), that is, fully fluorinated alkyl groups consisting solely of carbon and fluorine, having the formula CnF2n+1. Of particular interest are the compounds in which the number of carbon atoms m ea ch of the perfluoroalkyl groups (fluorocarbon groups) is m the range of 1 to 11 (i. e., n has an integer value of 1 to 11).

The compounds in which one or both of the fluorocarbon groups contains at least three carbon atoms constitute a sub-class of compounds having value as surface act ve agents and as starting compounds for making derivative compounds that are valuable surface active agents. In these compounds the presence of a perfluoroalkyl group containing at least three carbon atoms provides the molecule with a terminal fluorocarbon tail (or with two such tails if both groups contain three or more carbon atoms). The fluorocarbon tail is non-polar, highly stable and inert, and is both hydrophobic and oleophobic. Corresponding compounds containing only one or two carbon atoms in each fluorocarbon group do not possess appreciable surface active properties. It is also of critical importance that the fluorocarbon cham or tall be free of hydrogen atoms. In particular, the presence of even one hydrogen atom on the last or next to last carbon atom of the tail will markedly alter the surface active and solubility properties, render the tail polar nstead of non-polar, provide a point of attack for chem1cal reactions, and provide an opportunity for dehydrofluormation.

The compounds which have two identical fluorocarbon acyl groups united to the nitrogen atom can be represented by the equivalent formulas:

benzene rather than from the moisture inherently present in the system. (See Example 1.)

The present compounds can also be made by reacting 8 2,701,814 Patented Feb. 8, 1955 The reaction can be conveniently performed by refluxing thestartmg compounds and then separating the secondary amide by fractional distillation. It will be noted that the R1 and R: groups of the product compound will be different when the starting compounds have correspondingly difierent fluorocarbon groups.

The present compounds have the peculiarity, as compared with secondary amides of conventional organic chemistry, that they readily react with water and alkalies. They are acidic. When vigorously heated with base, ammonia is liberated.

The present compounds provide useful starting compounds for making the corresponding dihydro secondary amines, the bis(1,1-dihydroperfluoroalkyl) amines:

This can be accomplished by reduction of the amide with lithium aluminum hydride. These secondary amines are weak bases which form salts with strong acids (such as hydrochloride salts) in anhydrous solvents (such as ether). The hydrochloride salts are easily split by water at room temperature to regenerate the secondary amine, which is unusual since the regeneration of amines from amine salts usually requires the action of strong alkali. These amines and their salts have marked surface active properties when one or both of the perfluoroalkyl groups (R: and R'r) is a fluorocarbon tail containing three or more carbon atoms.

These secondary amines have utility for making acylamide derivatives, by reaction with carboxylic acid anhydrides and acid chlorides to obtain N,N-bis( 1,1-dihydroperfluoroalkyl) acylamides:

where R is a hydrocarbon or halogenated hydrocarbon group. ixamples are N,N-bis(1,l-dihydroperfluorobutyl) acetami e:

N-C CaF1H2C \CHI and N,N-bis 1, l-dihydroperfluorobutyl) perfluorobutyramide:

C a F 1H: 0

Reaction ofa secondary amine with acrylic anhydride or with methacrylic anhydride provides the corresponding N,N-bis( 1,1-dihydroperfluoroalkyl) acrylamide or methacrylamide, respectively. An example is N,N-bis(l,l-dihydroperfluorobutyl) acrylamide:

CtF1HzC CaH1H2C CH=CH1 These acrylamides and methacrylamides show great resistance to hydrolysis, and they can be polymerized to form stable and useful high polymers containing ahigh precentage of combined fluorine.

The foregoing derivatives and polymers are more fully described in the companion application of D. R. Husted o and A. H. Ahlbrecht, S. N. 368,825, filed of even date herewith.

The following experimental examples illustrate procedures'for making the subject compounds and provide further data on their properties.

Example 1 The apparatus was a 100 ml. 3-neck flask provided with a stirrer, thermometer and reflux condenser. A water bubbler was attached to the outlet of the condenser to indicate gas evolution. The flask was charged with 50 ml. of butyl benzene (serving as a solvent reaction medium) and then with 6.8 grams (0.05 mole) of phosphonitrilie chloride (PNClz) and 23.6 grams (0.1 mole) of the sodium salt of normal heptafluorobutyric acid (n-CaFrCOONa). The mixture was stirred and heated at 135-155 C. for 16 hours. There was some evidence of gassing and the mixture turned a darkbrown. The mixture was distilled and a crystalline material sublimed along with some solvent at 124-175 C. The solid was recrystallized from benzene and yielded 7 grams (34% yield) of colorless crystalline solid identified as substantially pure di-n-perfluorobutyramide:

This compound had a melting point of 82-83 C. Analysis showed 3.2% nitrogen (3.4% calc.) and 62.9% fluorine (65.0% calc.), and no phosphorous or chlorine. The infrared absorption spectrum showed the presence in the molecule of two C= and one N-H bonds.

Example 2 The material crystallized on standing, and the crystalline product had a melting oint of 82-83 C. Analysis showed 62% fluorine calc.) and 3.4% nitrogen (3.4% calc.). The saponification equivalent was 207 (calc. 204.5).

Example 3 A dry 250 ml. round-bottom flask fitted with a reflux condenser was charged with a mixture of 63 grams (0.3 mole) of trifluoroacetic anhydride and 34 grams (0.3 mole) of trifluoroacetamide. The mixture was refluxed for 16 hours and was then distilled. The fraction having a boiling point of 135-136 C. (at 744 mm.) was obtained in a yield of 45 grams and was identified as relatively pure diperfluoroacetamide:

(CFaCO) zNH This product was a colorless liquid and analysis showed 54% fluorine (calc. 54%) and 6.6% nitrogen (calc. The saponification equivalent was 102 (calc.

4 Example 4 A dry ml. round-bottom flask fitted with a reflux condenser was charged with a mixture of 7 grams (0.0136 mole) of pcrfluorodecanoic amide,

n-CoFmCONI-Ia and 15 grams (0.0148 mole) of perfluorodecanoic an- (n-CoFnCOhNI-I Anlal llsis showed 1.3% nitrogen (calc. 1.4%).

c arm:

1. As new and useful reactive fluorocarbon compounds,

the aliphatic diperfluoroacylamides having the formula:

where R: and R: are perfluoroalkyl groups that each contain from one to eleven carbon atoms.

2. As new and useful reactive fluorocarbon compounds, the aliphatic diperfluoroacylamides having the formula:

0 moi ing the formula:

(CnF2n+1C0)2NH -when n has an integer value of 3 to 11.

4. The di-n-perfluorobutyramide compound having the formula:

(n-CaFrCOhNH References Cited in the file of this patent UNITED STATES PATENTS Padbury et a1. Apr. 4, 1950 omen REFERENCES Bourne et al., "J. Chem. Soc. (London), Oct. .1952, pp. 4014-19. 

1. AS NEW AND USEFUL REACTIVE FLUOROCARBON COMPOUNDS, THE ALIPHATIC DIPERFLUOROACYLAMIDES HAVING THE FORMULA: 